ISP setup

RouterOS General
1

Hi!

I have a somewhat special question: I am customer of a small ISP that is providing me wireless internet. This ISP wants to change his network from bridged to routed. Because I used to be ISP myself (~15 years ago) and I have more experience in routing they asked for my help.

Back then, we didn’t use NAT etc. but routed ‘public’ IPs(subnets, at least /30) to our customers. I guess that won’t be possible in this case.
How do ISP manage this nowadays? I guess ‘simple’ customers just get NATed to one address, but how to cope with customers that want a public IP?
Add a pool of public IPs as loopback address on the core router and then dst-nat it to the private IP of the customer’s router? Or how do you do it?

Regards
Patrick

PS: Maybe another question. Will a RB1200 have enough ressources to make NAT for hundreds of customers?

2

It may depend on where you are. Here in Germany ISPs have pools of public addresses and dynamically distribute them via PPoE, etc. The only private addresses I came to see are used by ISPs as transfer nets.

We ourselves only serve business customers and therefore provide small subnets like /30, /29, /28. Because we got RIPE LIR in “the good old days” we have more than enough IPs (/19) and can afford to “sacrifice” 3 additional IPs when only 1 is needed (/30). Of course you could implement it more efficiently serving up to (max - 3 IPs) per Net.